Chapter 12.1 DNA
description
Transcript of Chapter 12.1 DNA
![Page 1: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/1.jpg)
Chapter 12.1Chapter 12.1DNADNA
![Page 2: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/2.jpg)
Genetics Genetics RecapRecap
• Mendel, through his experiments, concluded that a organism’s traits are a result of the inheritance of genes from that organism’s parents
• Mendel knew that this inheritance was due to some “factor” but was not able to identify what exactly it was– This left room for future scientists to
discover what these mysterious factors were
![Page 3: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/3.jpg)
Frederick GriffithFrederick Griffith• Studied pneumonia and its effects on mice
Smooth strain caused pneumoniaRough strain did nothing
• Injected mice with various mixtures of the two strains
![Page 4: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/4.jpg)
Griffith’s ExperimentGriffith’s Experiment1.Living smooth cells injected =
2.Living rough cells injected =
3.Heat killed smooth cells =
4.Heat killed smooth cells & living rough cells =
– Why did the mice die?
![Page 5: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/5.jpg)
Griffith’s ConclusionsGriffith’s Conclusions• Hypothesized that some factor
was transferred from the heat-killed cells into the live cells
• Bacterial transformation occurred a change in a bacterial trait
• Chemical is responsible for causing transformation Called it the transforming
principle• Little did he know that he found DNA
![Page 6: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/6.jpg)
Oswald AveryOswald Avery• Tried to find out what factor
caused the bacterial transformation
Destroyed all of the various macromolecules and tested to see if transformation still occurredWhen he destroyed DNA, no
transformation; proteins, lipids, and carbs still caused transformation
• Demonstrated that DNA was the transforming principle
![Page 7: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/7.jpg)
Enzymes that Enzymes that destroy the destroy the macromoleculemacromoleculess
The fact that The fact that there is no there is no S S strainstrain means means
that that transformation transformation did not happendid not happen
DNA is the DNA is the transforming transforming
principleprinciple
![Page 8: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/8.jpg)
Hershey and ChaseHershey and Chase• Used bacteriophages
viruses that attack bacteria
Consist of an outer protein coat and an inner core of DNA
![Page 9: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/9.jpg)
How Do Bacteriophages How Do Bacteriophages Work?Work?
• Bacteriophage lands on the plasma membrane of the bacteria
• Injects DNA into the bacteria
• Viral DNA inserts with bacterial DNA gets duplicated when bacteria goes through mitosis
• More viruses will be produced and eventually the bacteria explodes releasing all of the new viruses
http://www.youtube.com/watch?v=YG3d77SRWZI
![Page 10: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/10.jpg)
Hershey and Chase Hershey and Chase ExperimentExperiment
• Wanted to see what was responsible for causing transformation in bacteria– Was it the DNA inside the bacteriophage or the
protein coat surrounding the bacteriophage• Wanted to confirm Avery’s experiment
Labeled the protein coat with a radioactive sulfur isotope and the DNA with a radioactive phosphorous isotope so that they may follow where each part goes after the infection
![Page 11: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/11.jpg)
Hershey and Chase Hershey and Chase ExperimentExperiment
• Mixed solution of bacteriophage and solution of bacteria together and let virus work
• After a time, put mixture into a blender Purpose was to shake viral coats off of the bacteria
• Because the cell is heavier it will go to the bottom of the blender– This part will have the DNA from the virus
![Page 12: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/12.jpg)
Hershey and Chase Hershey and Chase ExperimentExperiment
![Page 13: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/13.jpg)
Hershey and Chase Hershey and Chase ExperimentExperiment
• When observing the blender found that the radioactive phosphorous was in the bottom part of the blender (inside the cells) while the radioactive sulfur was in the top part (empty protein coats)
• Conclusion – DNA causes transformation, NOTNOT protein
![Page 14: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/14.jpg)
DNA’s ResponsibilitiesDNA’s Responsibilities• Genes carry information from one
generation to the next
• Genes determine the heritable characteristics of organisms
• Genes can be replicated or copied exactly
![Page 15: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/15.jpg)
DNA’s ComponentsDNA’s Components• DNA is a nucleic acid
– It has monomers called nucleotides
• Each nucleotide is composed of three basic parts: 5 carbon sugar – deoxyriboseA phosphate groupA nitrogenous base
![Page 16: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/16.jpg)
![Page 17: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/17.jpg)
Nitrogenous BasesNitrogenous Bases• There are four nitrogenous bases
categorized into two groupsPurines: (two rings)
• Adenine (A)• Guanine (G)
Pyrimidines: (one ring)• Cytosine (C)• Thymine (T)
![Page 18: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/18.jpg)
DNA’s StructureDNA’s Structure• DNA can be considered to be like a ladder
The sugar and phosphate groups make up the backbone of the molecule, or the sides of the ladder– They alternate along the sides
The nitrogenous bases stick out of the sides of the sugarsugar– They make up the rungs of the ladder
![Page 19: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/19.jpg)
![Page 20: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/20.jpg)
Erwin ChargaffErwin ChargaffRealized the number of
A’s equals the number of T’s and that the number of G’s equals the number of C’s
• Base pairing rule
A = T G = C Purines Pyrimidines
![Page 21: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/21.jpg)
Rosalind FranklinRosalind FranklinUsed x-ray diffraction
to gather information about DNA structure
– Revealed that DNA is in helix form (coil or twisted ladder)
![Page 22: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/22.jpg)
Watson and CrickWatson and Crick• Made 1st 3-D model of a DNA molecule
– Used the work of Chargaff and Franklin to create this model
• DNA structure is called a double helix, in which two strands are wound around each otherThe two strands are connected by hydrogen
bonds
![Page 23: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/23.jpg)
![Page 24: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/24.jpg)
DNA and ChromosomesDNA and ChromosomesChromosomes are
tightly wound up DNA strands
• Increased organization allows for the tremendous length of DNA to fit into the nucleus of the cell
![Page 25: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/25.jpg)
Chromosome StructureChromosome Structure• DNA is tightly wound around proteins called
histones8 histones + DNA = nucleosome– These form chromatin
• Chromatin tightly wound up makes a chromosome
• http://www.youtube.com/watch?v=yqESR7E4b_8&feature=related
![Page 26: Chapter 12.1 DNA](https://reader035.fdocuments.in/reader035/viewer/2022062323/56815f6d550346895dce7681/html5/thumbnails/26.jpg)
Prokaryotic Prokaryotic ChromosomesChromosomes
• Prokaryotic chromosomes are located floating in the cytoplasm of the cell (not in the nucleus)They are circular in shape (not “X shape” like in
eukaryotes)